Preparation and x-ray characterisation of (Li<inf>2</inf>O.WO <inf>3</inf>)<inf>1-x</inf>(B<inf>2</inf>O<inf>3</inf>)<inf>x</inf> glasses

Abstract

Glasses in the system (Li2O.WO3)1-x(B 2O3)x were synthesised with equal molar ratios in Li2O and WO3 and 0.0≤x≤0.65 by the usual rapid quenching technique. From the analysis of x-ray diffraction data, it was found that for 0.0≤x≤0.25 the materials formed are crystalline, while for x≥0.30, glasses are obtained. The Rietveld method is used to characterise the crystalline systems obtained. On the other hand, the glassy phases are investigated by analysing the experimental radial distribution function RDF. The first observed real space correlations for the sample x=0.35 were located at 1.454 Å, 1.736 Å and 2.538 Å which are attributable to B-O, W-O and B-B atomic pairs, respectively. The corresponding atomic correlations for x=0.55 were at 1.479 Å, 1.960 Å and 2.289 Å. Concerning the boroxol group, in x=0.55 it is found to be in form of BO3 connected units having both nonbridging oxygen (NBO) and bridging oxygen (BO) types. In case of x=0.35, the units BO4 are formed indicating the change in the formed network units in medium range order MRO as a composition dependent.